1. Field of the Invention
The present invention relates to a map editing apparatus which facilitates editing of a map for a purpose such as generating a simplified map, while ensuring that predetermined position relationships within the map are preserved.
2. Description of the Prior Art
In the field of map editing, it is generally necessary that maps which result from such editing are detailed and accurate. In the case of map editing tools which are intended for general-purpose use, almost no functions are provided for actually editing maps themselves. However tools having some editing functions (such as the 2/3 dimension mapping system which has been developed by the Industrial Institute for Information Processing Advancement in Japan) have been produced.
Technology for a map editing apparatus which is capable of being switched between CAD (Computer-Aided Design) functions and attribute alteration functions has been disclosed in Japanese patent HEI 6-60136. With that apparatus, the editing functions utilize the same functions as those employed in CAD. Also, in Japanese patent HEI 8-77380, a system is described whereby degrees of priority are assigned to the constituent elements of a map in accordance with the strengths of their links to actual objects. When a map editing operation such as rotation processing is to be applied, with a plurality of map elements in the selected condition, alterations are applied in order from the elements having the lowest priority.
With prior art technology for map editing, the objective is usually to enable correction of the map data to be performed for the purpose of providing greater accuracy in the map. To some extent, the functions which are used as tools for CAD may be applied to such editing. However in the case of a map, it is also necessary to consider the question of maintaining conformity of certain position relationships within the map, when performing editing.
Furthermore in the case of a prior art technique whereby priority levels are assigned to the map elements, such that operations to change the shape of one element will result in linked changes in other elements, it is not always possible for a user to perform changes in shape within the map in accordance with the user's requirements.
Moreover there is a requirement for a capability whereby maps can be generated which, rather than being highly accurate and detailed, have been edited in such a way as to be made convenient to use and easily understandable. This can be achieved for example by emphasizing certain items of important information within the map and through the elimination of information which is not important, while leaving the accuracy of the map maintained at a certain level. Such types of map are generally designed by using conventional illustrator techniques. For that reason, such maps cannot be easily produced by an inexperienced person.
Furthermore, there is no map editing apparatus available which enables a user to specify that a special view of a particular small region in a map, such as a small picture providing an enlarged view or a birds-eye view of such a region, is to be automatically set into the map.